High reliability outdoor sonar prototype based on efficient signal coding

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 53; no. 10; pp. 1862 - 1872
• Main Authors: Alvarez, F.J., Urena, J., Mazo, M., Hernandez, A., Garcia, J.J., de Marziani, C.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-10-2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustics; Applied sciences; Atmospheric turbulence; Atmospheric waves; Coding; Computer science; control theory; systems; Control theory. Systems; Cross talk; Data Compression - methods; Encoding; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Fluctuations; Fundamental areas of phenomenology (including applications); General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mobile robots; Outdoor; Physics; Prototypes; Pulse compression; Pulse compression methods; Remotely operated vehicles; Reproducibility of Results; Robotics; Robotics - instrumentation; Robotics - methods; Robots; Sensitivity and Specificity; Sensor systems; Signal design; Signal Processing, Computer-Assisted - instrumentation; Sonar; Sonar navigation; Transducers; Ultrasonic technology; Ultrasonics, quantum acoustics, and physical effects of sound; Ultrasonography - instrumentation; Ultrasonography - methods; Autonomous system; Turbulence; Acoustic measurement; Navigation; Probabilistic approach; Moving robot; Crosstalk; Acoustic wave; Sonar; Data transmission; Travelling wave; Pulse compression; Robotics; Wave transmission; Indoor installation; Robustness; Reliability; Collision avoidance; Ultrasound
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2006.118

Many mobile robots and autonomous vehicles designed for outdoor operation have incorporated ultrasonic sensors in their navigation systems, whose function is mainly to avoid possible collisions with very close obstacles. The use of these systems in more precise tasks requires signal encoding and the incorporation of pulse compression techniques that have already been used with success in the design of high-performance indoor sonars. However, the transmission of ultrasonic encoded signals outdoors entails a new challenge because of the effects of atmospheric turbulence. This phenomenon causes random fluctuations in the phase and amplitude of traveling acoustic waves, a fact that can make the encoded signal completely unrecognizable by its matched receiver. Atmospheric turbulence is investigated in this work, with the aim of determining the conditions under which it is possible to assure the reliable outdoor operation of an ultrasonic pulse compression system. As a result of this analysis, a novel sonar prototype based on complementary sequences coding is developed and experimentally tested. This encoding scheme provides the system with very useful additional features, namely, high robustness to noise, multi-mode operation capability (simultaneous emissions with minimum cross talk interference), and the possibility of applying an efficient detection algorithm that notably decreases the hardware resource requirements